I have a USB hub mounted on the right port (powered) - usually connected and active are a logitech mouse and my HP printer, another cable is used on occasion to hook to a camera, and a hard drive for backups (kept powered off when not doing backups).
I have found that a Cowon iAudio U3 mp3 player would not mount on the left USB port. It does mount on the right (when I disconnect the hub, not through the hub) AND it does connect on the left port if the hub is not on the right.
I also get weird lockups if I have my Altec Lansing USB headset in the left USB port (it works the first time inserted), but if I remove it and later re-insert the headset, my entire system freezes.
I've read almost every post I could find on faulty ports, with no real pattern, and as this is hardly crippling, cannot even see any value of sending it away to Apple and lose 2 weeks of work time (I went through 2 cycles of that last summer with a bad fan assembly and logic board issues).
I'd just be wary of hubs - My use is mainly to reduce some desktop clutter and avoid all the cable swappings, but mine is looking now like a suspect.
There is a history on this forum regarding left vs. right USB port operation. In some cases, the left port doesn’t support certain devices/configurations and it is an inherent issue with the MacBook Pro. It isn’t a failure of your system. Regards,